Provide information on the potential carcinogenicity of a variety of chemicals, including clinically useful antineoplastic immuno-suppressive agents, in nonhuman primates. Provide for the production of model tumor systems in primates so that the potential usefulness of various therapeutic modalities in treating such tumors in humans can be assessed. Additional objectives include the development of models for chemoprevention of chemically-induced tumors and the development of various biological markers and diagnostic tests and procedures for detecting premalignant lesions as well as frank neoplasia.